Flexible cable



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' FLEXIBLE CABLE Filed Feb. 6. 1929 /0 HARD wmf (w50/A.)

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Patented Apr. 25, 1933 UNITED STATES PATENT OFFICE A HARTWELL W. WEBB,OF FLINT, MICHIGAN, ASSIGNOR T0 A C SPARK 0F FLINT, MICHIGAN, A COMPANY0F MICHIGAN PLUG COMPANY,

FLEXIBLE CABLE Application led February 6, 1929. -Serial No. 337,984.

cessive layers of wire wound thereabout.

In the present instance four successive layers are wound about the corewire.

Flexible shafts now in use either use no core wire at all or a core Wiremade of steel. It has been determined experimentally that flexibleshafts using a core wire of steel are objectionable for the reason thatthe steel core breaks down first due mainly to fatigue The core wire ofa flexible shaft is subjected to a very large number of bends in thecourse of its use and it is therefore highly necessary that the corestand up under all degrees of tension and possible demand in the trade.Steel is also objectionable for the reason that it does not readily lenditself to uniform elongation, and this uniform elongation is a desirablefeature in the art of flexible cable manufacture. A tinned steel wirewas also used as a core wire but tests also showed that the tinned corewire broke down first. These experiments led to the use of a phosphorbronze core `which is relatively much softer than steel and has theproperty of greater elongation than steel wire, and at the same time hashigh tensile strength. In addition phosphor bronze is capable of uniformelongation while the elongation in steel is liable to be irregular. Asoft bronze wire is also extremely resistant to fatigue and is well ableto stand up under all requirement of actual use.

A Achrome vanadium wire might beused as a core wire well as a phosphorbronze wire. However the objection to chrome vanadium steel is that itis costly and it is also understoodthat it is diflicult to draw thiswire ine enough for use in iexible cables. Chrome vanadium steel has thedesired anti-fatigue properties but not the anti-friction properties.

Another reason for the use of a phosphor bronze core and a first layerof phosphor ing between the first andV second layers. It

is between the phosphor bronze core and the second layer that the mainportion of the internalheat in the shafting is generated and the greaterfriction developed. At the median point on the radius of a cross seotionof the cable, the alternate tension and compression strains have nomeans of relief by corresponding change from circular to oblate sectionof the individual coils as have the outer layers and metal to metalfriction must be as little as possible at this point.

The core wire of phosphor bronze is preferably of a larger diameter thanthe diameter of phosphor bronze wire Wound thereabout. The core wire andphosphor bronze layer form a core and over the phosphor bronze corethere are wound two successive layers of relatively hard wire, or whatis known asOA?) carbon wire. Over the outer layers there is wound .asingle layer of relativclysoft wire, or what is lknown as 0.10 carbonwire.

The use of a soft outer wire is for the l purpose of making it easier toretain the ends of the cable together after it is severed. If a hardwire is used on the outside and the cable severed, there is a greattendency for the ends to unravel in fascicular form.

If the outer soft wire layer is wound on the outermost hard wire layer,there is a tendency for the harder wire to embed itselfin the softerwire. This embedding is increased as the wire passes through thewithdrawal rollers which pull the product from the cable winding machineand is further increased in the wire straightener. When a cable havingan outer layer of soft wire is severed there is a tendency for the innerhard steel layers to unwind out against the outer soft wire layer, whichis additive to the embedding of the two layers into each other, tothereby prevent unraveling. Unraveling is prevented by the fact that theinner layer has a. tendency to unravel and the outer layer has not.

The old way of manufacturing cable is' shown and described in thepatents to Webb, 887,159 and 887,160, May 12, 1908. These patentsdescribe a coreless iexible shaft in which the shaft as a whole isstretched after it is completed. In stretching, the inner or smallerdiameter layers are diminished in diameter a greater amount than theouter layers which leaves a relatively small space between adjacentlayers and accordingly decreases friction. This progressively increasingrate of decrease in diameter from the outer to the inner layer is validonly where the wires are of nearly the same gage of' wire. For reasonsof economy and to provide equal crossing angles in successive layersitis desirable to progressively increase the gage of 4the wire as thelayers are built outwardly and the formula in which space is obtainedbetween successive layers therefore no longer holds.

Accordingly in the present invention use is made of wires havingdifferent diameters.

Hence it is advisable, after applying eachlayer, to mechanically massagethat layer upon the surface of its subjacent layer. This effects astretching of the layers, oblates the wire section to' give the longdiameter axis longitudinal with the structure, and as the frictionpoints, which it is necessary to lubricate, are between the individualwires themselves and between the layers, the process of oblatingthe wiresection, gives lubrication space between the wires and the layers. Thestretching 4and massaging is accomplished by the wire straightened inuse on the cable winding machines.

In passing the successive layers of wire through a pair of withdrawingrollers and through the wire straightener the softer wires are eithercaused to dig into each other or become somewhat flattened at theircontacting surfaces, or the harder wire will dig thereinto. This is truewith reference to the phosphor bronze core and first layer, between thephosphor bronze layer and hard wire layer, and between the outer hardwire layer and outermost soft wire layer.

On the drawing: 1

Figure 1 shows a view of the flexible cable with the individual strandsin separate relation to show the composite nature of the shafting.

Figure 2 is an enlarged view of the core wire and first layer ofphosphor bronze wire.

Figure 3 is a section through the phosphor bronze core and phosphorbronze layer.

Figure 4 is a section through the completed shaft.

Referringto the drawing the numeral 2 indicates a flexible shaft as awhole. The flexible shaft comprises the phosphor bronze core wire 4, thelayer 6 of phosphor bronze wire wrapped therearound, the succeedinglayers 8 and 10 of hard wire, and the outer layer 12 of soft wire. Thecoi-e4 of phosphor bronze wire preferably has a diameter of .017 inchwhile the phosphor bronze layer 6 wrapped thereabout is preferablycomposed of wires having a diameter of .013 inch. This core wire andphosphor bronze layer are shown in Figures 2 and 3, the proportionsbeing considerably exaggerated for purposes of clearer illustration.

`In wrapping the layer 6 on the core Wire 4 the cable Winding machinetightly wraps the wire 6 about the core wire and causes a slightdeformation at their contacting surfaces. This deformation may bedescribed as one wire digging into the other or as the flatening of thewires at their contacting surfaces. As the wire leaves the wrapping noseor head it is vpassed through a pair of withdrawing rolls which tightlypress the wire between them and cause a further oblation or deformationindicated generally at 14 in Figures 2, 3, and 4.

' As the wire leaves the withdrawing rolls it is passed through a rotarywire straightener which f urther oblates and elongates or stretches theproduct and provides space foi` lubrication. See patents to Stone, 359,-410, and Sisum, 488,227, for illustrations of .the applications of awire straightener and withdrawal or take-up rollers.

The core wire 4 and the layer of phosphor bronze Wire 6, after passingthrough the withdrawing rolls and the wire straightener are quiteintimately united and are relatively immovable and Aform a phosphorbronze core comprising the core wire and the phosphor bronze layer.

The core, indicated as a whole at 16, 1s then passed through a machineand the layer 8 of hard wire of a diameter of preferably .013 inchwrapped therearound. The hard wire is tightly wrapped and due to thedifference in hardness between the hard wire layer 8 and the phosphorbronze core 6 the hard wire digs into the phosphor bronze.

lThis deformation or digging is further accentuated as the productpasses through the withdrawing rolls and the wire straightener.

A second layer 10 of hard wire of a diameter of preferably .015 inch isthen wrapped about the layer-8 which is followed by the layer 12 ofrelatively soft wire of a diameter of preferably l017 inch. Owing to thedifference in hardness between hard wire layer 10 and soft wire layer 12thehardenwire digs, imbeds itself into or slightly deforms the softerwire to thercb form a morel intimate connection between t e two. This isof advantage when cutting the wire to length in that it preventsunraveling at the end. There is a slight unraveling due to the outwardpressure of the hard wire layer, but the unraveling is only slightbecause of the rather intimate interconnection between the two outerlayers and to the fact that they are wrapped in opposite directions.

As will be noted' from Figure 1 the successive layers are wrapped inopposite directions in a well-known manner.

n Owing to theffact that each successive layer after it is wrapped onits subjacent layer is passed through a pair of withdrawing rolls andawire straightener the cable is stretched or elon ated to the desireddegree and when the glial or outer soft wire layer 12 is added the cablewill be finished and ready for use after it leaves the Inachine. Nostretching will be required as in the Webb Patents 887,159 and 887,160,previously :referred to.

Exactly the same result as regards the separation of adjacent coils haspreviously been secured by stretching the cable when completed to about11A; times its own diameter per foot in a device whereby it is runthrough two pairs of rolls, the second pair of which rotate at greaterspeed than lthe first pair. The result was satisfactoryl but caused anextra operation and did not oblate the wire so that hard spots remainedin the cable.

The completed cable has also previously been swagedxin a rotary swage.This was satisfactory in oblating the wire and giving s'pacezbetweensuper and'subjacent layers,

but caused the wires of a layer to close on each other resulting inshort life under load.

The rotary massaging of each layer as it is formed, on the subjacentlayer, effects both these objects of stretching and oblationsatisfactorily and as phosphor vbronze has extremely high and uniformelongation combined with great tensile strength it was adopted for thecore wire, and for the first layer because of its anti-frictionproperties with hard steel.

After the final product leaves the cable winding machine it is cut tolength in accordance with the disclosure of the 'Webb Patents 1,808,198and 1,808,194.

While I have shown and described four layers of wire, it is within thescope of the invention to use more or less layers and the process offorming the cable may be stopped after winding any of the hard wirelayers. The cable may also be made by using two outer layers of softwire, or one hard wire and one soft wire layer.

I claim:

1. In a flexible driving shaft, a phosphor bronze core comprising aplurality of tightly interwound wires, said wires digging into eachother or having flattened. contacting sides so as to prevent relativemovement, and one or more layers of wire over said core.

2. In a flexible driving shaft, a phosphor bronze core wire, a layer ofphosphor bronze wire over said core wire, and two layers of hard steelwire over said layer of phosphor bronze wire.

3. In a flexible .driving shaft, a phosphor bronze core wire, a layer ofphosphor bronze wire over said core wire, said core and layer beingrelatively immovable, two layers of hard steel Wire over said layer, andan outermost layer of soft steel Wire.

4. In a flexible driving shaft, a phosphor bronze core Wire, a layer ofphosphor bronze wire over said core wire, said core and layer beingrelatively immovable, a lplurality of layers of hard steel wire oversaid layer, and an outermost layer of soft steel wire.

-5. In a flexible driving shaft comprised of a plurality of wires, aphosphor bronze core wire, and a plurality of layers of Wire wound inalternately opposite directions over said core wire.

6. In a flexible driving shaft comprised of a plurality of wires, aphosphor bronze core comprising a plurality of wires, and a plurality oflayers of wire Wound in alternately opposite directions over said core.

7. In a flexible driving shaft comprised of a plurality of wires, -aphosphor bronze core comprising a core Wire and a -layer of wire woundthereover, and a plurality of layers of wire wound in alternatelyopposite directions over said core.

8. In a flexible driving shaft comprised of a plurality of wires, aphosphor bronze core comprising a plurality of relatively immovableWires, and a plurality of layers of wire wound in alternately oppositedirections over said core.

9. In a flexible driving shaft comprised of a plurality of wires, aphosphor bronze core comprising a plurality of wires having differentdiameters, and a plurality of layers of Wire Wound in alternatelyvopposite directions over said core. y

10. In a flexible driving shaft comprised of a plurality of wires, aphosphor bronze core, and one or more layers of hard wire wound inalternately opposite directions over said core.'

11. In a flexible driving shaft comprised of a plurality of wires, aphosphor bronze core wire, a layer of phosphor bronze wire over saidcore wire, and one or more layers of hard wire wound in alternatelyopposite directions over said phosphor bronze layer.

12. In a flexible driving shaft comprised of a plurality of wires, aphosphor bronze core comprising a plurality of wires, and one or morelayers of hard wire Wound in alternately opposite directions over saidcore.

13. In la flexible driving shaft comprised of a plurality of wires, aphosphor bronze core, and two layers of hard steel wire wound inalternately opposite directions over said core.

14. In a flexible driving shaft comprised of a plurality of wires, aphosphor bronze core, one or more layers of hard wire wound inalternately opposite directions over said core, and an outermost layerof soft Wire' wound in a direction opposite to its adjoining layer.

15. In a flexible driving shaft comprised of a plurality of Wires, aphosphor bronze core comprising a plurality of Wires7 one or more layersof hard wire Wound in alternately opposite directions over said core,and an outermost layer of soft Wire wound in a direction opposite to itsadjoining layer.

16. In a flexible driving shaft comprised of a plurality of layers ofWire wound in alternately opposite directions, a phosphor bronze coreWire, a layer of phosphor bronze Wire Wound over said core Wire,- thewire of said layer having a diameter dilferent from the diameter of thecore Wire, a plurality of layers of hard steel Wire wound in alternatelyopposite directions over said phosphor bronze Wire, the Wire of one hardsteel Wire layer having a diameter different from the diameter to theWire of the adjacent hard wire layer, and an outermost layer of softsteel Wire Wound in a direction opposite to the winding of .its adjacentlayer.

17. In a flexible driving shaft comprised of a plurality of Wires, aphosphor bronze core Wire, and a plurality oflayers of Wire wound inalternately lopposite directions over said core Wire, not more than twoof said layers having their Wires 0' the same diameter. j

18. In a flexible driving shaft comprised of a plurality of layers ofWire Wound in alternately opposite directions, a phosphor bronze core7 aplurality of layers of Wire Wound in alternately opposite directionsover said core, the wire of one layer having a diameter differ :nt fromthe 'Wire of the adjacent layer, and an outermost layer of soft WireWound in a direction opposite to the winding of its adjacent layer.

In testimony whereoi1 I aiiix my signature.

HARTWELL W. WEBB.

